Implement formatters for ls operation

[shagren]

Not implemented:

• Tests

[shagren]

it's generator. We can use click.pager() here instead click.echo()

[asvetlov]

1. Why?
2. The change is not related to the PR

[shagren]

1. It`s right. REGEXP's variables works from project root but DIR's variables from python folder.
2. Yes. Can move to separate mini-pr

[asvetlov]

May I ask why did you add all these options?
Where is the corresponding discussion?
#427 mentions only -l and (indirectly) -h.

[shagren]

I investigated how work gnu ls and find that it provide 3 formats/layouts according scenarios from #427:

• long, detailed file info, one file per line
• vertical, file names which displayed in few columns and sorted from top-down, left-right. It's deault layout for terminal.
• single-column, file names, one per line. This layout will be enabled automatically when stdout is not terminal and layout is not specified.

Then i learned that we need some more that "-l" switch and add --format option with one additional value commas and next shortcuts: -l, -x, -1, -C, .
After that I consider that commas format often require quoting for file names and add --quote-name(and alias -Q) and inveredt(but default) options --literal(with alias -N)

Also i found that ls sort files by alphabet by default and add --sort option with shortcuts(-f, -S, -t, -U, -r / --reverse).

We haven`t before any time field in ls output but we have modification_time field in FileStatus. As I remember this fields was added some later than neuro storage ls realized, and than this information was missed. I add this information to long format and corresponding options --time-style, --full-time.

There left only one option which not follow initial discussion: --group-directories-first.

That's all.

[asvetlov]

I think the PR cannot land as is: rare options are not only useless but actually harmful.
They blow documentation size and make learning the tool harder without a strong reason.

Also, it makes the support of existing code harder than needed

[codecov]

Codecov Report

Merging #469 into master will increase coverage by 0.3%.
The diff coverage is 96.8%.

@@            Coverage Diff            @@
##           master     #469     +/-   ##
=========================================
+ Coverage   90.61%   90.91%   +0.3%     
=========================================
  Files          36       37      +1     
  Lines        2439     2553    +114     
  Branches      282      313     +31     
=========================================
+ Hits         2210     2321    +111     
- Misses        178      179      +1     
- Partials       51       53      +2

Impacted Files	Coverage Δ
python/neuromation/cli/rc.py	93.96% <100%> (+0.06%)	⬆️
python/neuromation/cli/formatter.py	100% <100%> (ø)	⬆️
python/neuromation/cli/main.py	56.06% <80%> (+1.03%)	⬆️
python/neuromation/cli/storage.py	96.03% <85.71%> (-1.77%)	⬇️
python/neuromation/cli/files_formatter.py	99.01% <99.01%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update e3705c2...a6ec4a4. Read the comment docs.

[shagren]

@asvetlov , please check now

[asvetlov]

Looks good!
A few comments

[asvetlov]

LGTM!